Why not?
The grey is kinda dull looking, so a little color won't harm the car.
You should use a good primer, then the paint doens't matter to much.
Also give it several layers of clearcoat.
That should do it...

duplicolor vinyl dye works and looks the best. clean it well, scuff with green scratch pad, clean it even more, then use duplicolor adhesion promoter then dye it. I blacked out my light gray and left the dark alone looks awesome. I did mine back in February 2005 and the only place it shows wear is on my drivers armrest pad. I use Armor all original, its not too shiny but it looks bright.